Re: "double meaning"

: : : Out of a novel by Elmore Leonard (Maximum Bob):
: : : "He had to push her aside to slide the glass door open enough to draw a clear bead on the gator, Jesus Christ, a big one he estimated to run ten or twelve feet."
: : : What's the exact meaning of "draw a clear bead". I understand it, but I prefer get wise advice. Besides, could this be also related somehow to shooting a weapon (the guy sliding the door open is holding a gun)?
: : : I ask this because E. Leonard is quite good (and often) using double meaning words or idioms. Thanks.

: : One meaning for bead is "a small metal knob on a firearm used as a front sight." (Merriam-Webster online)